<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - OffscreenCanvas Picking</title>
    <style>
    html, body {
        height: 100%;
        margin: 0;
    }
    #c {
        width: 100%;
        height: 100%;
        display: block;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
  </body>
<script type="module">
import { state, init, pickPosition } from './shared-picking.js';

let sendMouse;

function startWorker( canvas ) {

	const offscreen = canvas.transferControlToOffscreen();
	const worker = new Worker( 'offscreencanvas-worker-picking.js', { type: 'module' } );
	worker.postMessage( { type: 'init', canvas: offscreen }, [ offscreen ] );

	sendMouse = ( x, y ) => {

		worker.postMessage( {
			type: 'mouse',
			x,
			y,
		} );

	};

	function sendSize() {

		worker.postMessage( {
			type: 'size',
			width: canvas.clientWidth,
			height: canvas.clientHeight,
		} );

	}

	window.addEventListener( 'resize', sendSize );
	sendSize();

	console.log( 'using OffscreenCanvas' ); /* eslint-disable-line no-console */

}

function startMainPage( canvas ) {

	init( { canvas } );

	sendMouse = ( x, y ) => {

		pickPosition.x = x;
		pickPosition.y = y;

	};

	function sendSize() {

		state.width = canvas.clientWidth;
		state.height = canvas.clientHeight;

	}

	window.addEventListener( 'resize', sendSize );
	sendSize();

	console.log( 'using regular canvas' ); /* eslint-disable-line no-console */

}

function main() { /* eslint consistent-return: 0 */

	const canvas = document.querySelector( '#c' );
	if ( canvas.transferControlToOffscreen ) {

		startWorker( canvas );

	} else {

		startMainPage( canvas );

	}

	function getCanvasRelativePosition( event ) {

		const rect = canvas.getBoundingClientRect();
		return {
			x: ( event.clientX - rect.left ) * canvas.width / rect.width,
			y: ( event.clientY - rect.top ) * canvas.height / rect.height,
		};

	}

	function setPickPosition( event ) {

		const pos = getCanvasRelativePosition( event );
		sendMouse(
			( pos.x / canvas.width ) * 2 - 1,
			( pos.y / canvas.height ) * - 2 + 1 ); // note we flip Y

	}

	function clearPickPosition() {

		// unlike the mouse which always has a position
		// if the user stops touching the screen we want
		// to stop picking. For now we just pick a value
		// unlikely to pick something
		sendMouse( - 100000, - 100000 );

	}

	window.addEventListener( 'mousemove', setPickPosition );
	window.addEventListener( 'mouseout', clearPickPosition );
	window.addEventListener( 'mouseleave', clearPickPosition );

	window.addEventListener( 'touchstart', ( event ) => {

		// prevent the window from scrolling
		event.preventDefault();
		setPickPosition( event.touches[ 0 ] );

	}, { passive: false } );

	window.addEventListener( 'touchmove', ( event ) => {

		setPickPosition( event.touches[ 0 ] );

	} );

	window.addEventListener( 'touchend', clearPickPosition );

}

main();

</script>
</html>

